mxge(4): avoid clang 21 warning in NO-IP configuration
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Authored by dim on Jan 15 2026, 11:33 AM.

Details

Reviewers

ehem_freebsd_m5p.com
imp
jhb
jhibbits
zlei

Commits

rG1b02df092f17: mxge(4): avoid clang 21 warning in NO-IP configuration
rG6380e5311239: mxge(4): avoid clang 21 warning in NO-IP configuration
rG0b52fb50695e: mxge(4): avoid clang 21 warning in NO-IP configuration
rG74cac745fe30: mxge(4): avoid clang 21 warning in NO-IP configuration

Summary

Building the LINT-NOIP kernel on amd64 with clang 21 results in a
-Werror warning similar to:

sys/dev/mxge/if_mxge.c:1846:44: error: variable 'sum' is uninitialized when passed as a const pointer argument here [-Werror,-Wuninitialized-const-pointer]
 1846 |                     cksum_offset, sizeof(sum), (caddr_t)&sum);
      |                                                          ^~~

Indeed, if both INET and INET6 are undefined, sum is never
initialized.

I don't know if it makes sense to set a checksum in the TCP header at
all in that configuration, but a simple solution to avoid the warning is
to skip the m_copyback call completely.

Alternatively, sum could be set to zero or another appropriate value,
but I have no idea what is correct here.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Passed

Unit

No Test Coverage

Build Status

Buildable 69937
Build 66820: arc lint + arc unit

Event Timeline

dim requested review of this revision.Jan 15 2026, 11:33 AM

dim created this revision.

Harbormaster completed remote builds in B69909: Diff 169767.Jan 15 2026, 11:33 AM

Initialize sum to zero instead, otherwise we get a "unused variable
'sum'" warning, which also breaks the build.

It's really an esoteric case: INET and INET6 are disabled, and then you
would have to hit a path where TSO is used. Seems very unlikely, and in
that case a zero checksum is probably fine.

Harbormaster completed remote builds in B69937: Diff 169911.Jan 16 2026, 9:07 PM

jhibbits accepted this revision.Jan 16 2026, 9:14 PM

This revision is now accepted and ready to land.Jan 16 2026, 9:14 PM

Closed by commit rG74cac745fe30: mxge(4): avoid clang 21 warning in NO-IP configuration (authored by dim). · Explain WhyJan 16 2026, 11:32 PM

This revision was automatically updated to reflect the committed changes.

dim added a commit: rG74cac745fe30: mxge(4): avoid clang 21 warning in NO-IP configuration.

dim added a commit: rG0b52fb50695e: mxge(4): avoid clang 21 warning in NO-IP configuration.Mon, Jan 26, 8:42 AM

dim added a commit: rG6380e5311239: mxge(4): avoid clang 21 warning in NO-IP configuration.

dim added a commit: rG1b02df092f17: mxge(4): avoid clang 21 warning in NO-IP configuration.